Uber redirecting and popups - Search engine redirecting

Hi
This seems to be the problem of the month but i have a problem with my google searchs redirecting and giving me pop ups.

I use Firefox 3 and Widows XP , i used to have AVG 8 which stopped updateing so swapped to avast!.

My problem is asfollows: i do a search , click on a resulr and it opens a new tab which is redirected to another site. I have not had any porn or such ( now i said it i will!) but i do get pop ups which seems to come in either ones or 3-4 a click. The other thing is one click on a result redirects ,a second click takes me to th site i am going to.
I had Spy bot S&D which stopped opening , i tried to re-install but it never worked. Avast! has picked up on 3 virus's and cleared then but i still have my little pain.

To finish it off, on turning my laptop on over the last week it hangs on the desktop at loading and finally ends with the mouse cursers freezing on the desktop. This i have found i can get around by turning off the wireless and then turning it back on after it has fully loaded.